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A natural biopolymer bilayer film based on chitosan and bacterial cellulose with a protective layer of pullulan was developed by a two-step solution casting method. Curcumin was incorporated as an active antioxidant and antibacterial agent into the inner layer. The films with different curcumin concentrations were systematically characterized. Fourier transform infrared spectroscopy and X-ray diffraction analyses showed high compatibility between curcumin and the polysaccharide matrix through intermolecular interactions, which was verified by enhanced mechanical and barrier properties. The curcumin incorporation improved the thermal stability by >35.4 %, along with lower visible and ultraviolet light transmittance (< 8.6 %) and water solubility (< 25.1 %). The film had both antibacterial and antioxidant properties, and the sustained release of curcumin was largest (> 58.8 %) in the fatty food simulant lasting for over 155 h. The results suggested that the film containing 0.2 % curcumin had ideal physical and functional properties, suggesting its potential as a novel packaging material for the preservation of high-fat food. [ABSTRACT FROM AUTHOR]

Probiotic supplements have been widely employed to change gut microbiome compositions for the treatment of numerous human disorders since gut flora has a tight association with human health and disease. However, the viability of probiotics has been a major barrier to the application of probiotic products. Here, we developed an electrostatically reinforced and sealed nanocellulose-based macrosphere for probiotic encapsulation. The inside porous gel sphere provides abundant and relatively independent porous spaces for probiotics to live in. The introduction of chitosan hydrochloride (CHC) and alginate (ALG) strengthened the gel structure and contributed to the formulation of a multi-layered structure with pH-responsive properties. The mild strengthening and coating processes avoid severe damage to the sensitive probiotics in the processing process, and the synthesized multi-layer macrospheres could protect probiotics from gastric acid and bile salt conditions. In addition, the dissolvability of the outer shell and the stable inner porous skeleton in intestinal conditions allow the gradual release of the entrapped probiotics in targeted environments. Overall, this work suggests the electrostatically reinforced and sealed nanocellulose-based macrospheres are ideal materials for the probiotic delivery application. [Display omitted] • TEMPO-oxidized cellulose nanofibers crossed by Ca2+ were designed as inner core. • The inner core can provide abundant porous spaces for probiotics to live in. • Chitosan hydrochloride and alginate were introduced to strengthen gel structure. • Composite macrosphere is of multi-layered structure with pH-responsive properties. • The macrosphere can protect probiotics from gastric acid and bile salt conditions. [ABSTRACT FROM AUTHOR]